What is the frequency of the system clock if WDT overflows?

Question:

If the internal oscillator is selected by watchdog timer (WDT), is the overflow time set to MIN0.2,TYP0.4SEC regardless of frequency of the system clock?

Answer:

With the internal oscillator, setting overflow time is made independently from the system clock and sub-clock. The time to the generation of internal reset by counting up from 0 to 255 is 0.2-typ0.4sec.